Abstract: For use with a front-end loader etc, the coupler-assembly provides a rigid connection between the pivoting arm-end and the bucket. Included is a slider-block, guided in slide-guides and slider-slots in side-plates of the frame of the arm-end. Sliding the block using a hydraulic slider ram, wedges the bucket lugs tightly into the frame. The slider-ram is integrated into and moves with the block. A lock-spring urges a lock-bolt into position to lock the bucket-lug to the arm-end frame. A lock-ram releases the lock-bolt, to permit dis-engagement.